Spark plug



June 16, 1936. c PATOCK 2,044,325

' SPARK PLUG Filed May 25, 1933 [HD87- CharlafiPaibcla l atentedalune 16, 1936 UNITED STATES sranx PLUG Charles Patock, Chicago, 111., assignor of onethird to Frederick E. Hummel, Chicago,.Ill.

Application May 25, 1933, Serial No. eta-ms 4 Claims. 01. 123-169) My invention relates to spark plugs of the type ordinarily employed in connection with internal combustion engines,' an object being to provide an improved device of the above character having certain structural and operating features.

One of the features of my invention resides in the provision of a. construction permitting the use of removable or interchangeable electrodes. I understand that spark plugs with removable electrodes havev been heretofore provided, but one of the features of my invention is the provision of such removable electrodes which remain tight and prevent leakage although carried through the center of the central porcelain.

Another feature of my invention is the provision of a protective cap arrangement adapted to .exclude moisture and water from parts of the plug usually affected thereby. More particularly it resides in the provision of a protective cap readily applied over the exposed part of the center porcelain so as to exclude water such'as might crack the porcelain when it is heated. For a better understanding of my invention reference is to be had to the accompanying draw ing in which t Fig. 1 is a cross-sectional view of the preferred form of my improved plug; Fig. 2 is a side elevation of the same;

construction; and g Fig. 4 is a modified form of cap construction. Referring now more in detail to the preferred form of my invention as shown in Figs. 1 and 2, I provide a suitable body portion A to which a removable outer electrode 5 is applied. This electrode is inserted by its shank 6 into the threaded sleeve portion of the body A being secured in place bya set screw and lock nut set into a depression 8 formedin the side of the plug body A. Thus the set screw and its lock nut are maintained beneath the outer surface of the body or at least flush therewith. As to the center electrode, this is removably carried in the porcelain center 9 held in place by the usual nut l0 and suitable washers. The center or rod electrode II is preferably threaded into the lower end of the porcelain l by a threaded sleeve l2 permanently secured to the center elec-' trode Ii. This sleeve l2 extends into a lower flange or shoulder l 3 which rests against a washer ll of metal'or asbestos. The upper end of the center electrode ll extends freely into an upper 5 terminal block I! having a threaded portion Ii objections referred to. Fig. 3 is a modified form of removable electrode which is threaded into the upper end of the porcelain 9. Theelectrode II is held in the terminal block l5 by a set screw I1 and lock nut so as to make positive electrical contact between the parts H and IS. The upper end of the ter- 5 minal block is provided with a suitable terminal nut i8 for securing the usual conductor to the spark plug.

By the improved construction shown and described the center electrode is positively held 10 at its opposite ends so that any expansion or contraction thereof will notopen up the joint at the lower end at the washer M. In other words by screwing this center electrode into the center porcelain, although the center rod may expand 15 from heat, a tight joint is maintained. One of By screwing the electrode into the porcelain at 25 the lower end and securing it in the terminal block which is threaded into the upper end of the porcelain, I maintain a tight joint at both ends of the rod thus overcoming the previous i 30 As previously referred to, I also provide a protectlve cap I! for the porcelain, this being in the nature of a cup made of suitable material which will stand heat and moisture such as treated fiber, this cap being held between the terminal block 35 I5 and the top of the center porcelain 9. The cap I! extends down into contact with the body A so is to provide a water-tight joint and thereby prevent the seepage or splashing of water against the porcelain 9. This is particularly of 0 importance where the spark plug is used on a motor boat or exposed engine, whereby the use 4 of a large protective cap for the spark plug is eliminated. 45

In Fig. 3 I have shown a modified form of center electrode II in which the threaded sleeve I2 is not providedthat is, in this type of center electrode the rod is pressed up into the porcelain and held there by the set screw in the upper 50 terminal block as in Fig. 1.

In Fig. 4, I have shown a modified form of a cap is. In this arrangement the cap extends over the top of the terminal block is and is held in place by a lock nut 20.- Thus the cap may be removed and replaced without removing the terminal block l5.

From the foregoing it will be apparent that I have provided an improved spark plug structure having readily removable electrodes so constructed as to be readily removable and at the Although I.have illustrated and described preierred forms of my invention, I contemplate making it in other ways than that shown and described, and therefore do not desire to be limited to these exact constructions but aim to cover all that which comes within the spirit and scope of the appended claims.

What I claim as new and desire to protect by.

Letters Patent oi the United States is:

1. A spark plug having a center porcelain insulator, a top terminal block threaded into the insulator, a center rod electrode removably inserted through the insulator and having a plain end extending into a closed bottom opening in the terminal block and a set screw extending through the side of the block for holding the rod in the terminal block.

2. A spark plug having a center porcelain insulator, a top terminal block secured to the insulator, a center rod electrode, and means for axially fixedly but removably securing one end of the rod to the terminal block and the other end removably but axially fixedly in direct contact with the lower end of the insulator, said insulator having a central opening through which the rod extends, which is larger than therod to aflord clearance, and said rod being sealed in the terminal block and at the lower end of the insulater to prevent exit of exploded gas through the porcelain insulator.

3. A spark plug having a center porcelain insulator, a topterminal block secured to one end or the insulator, a center rod electrode, and means for axially fixedly but removably securing oppothe other end 01' the insulator respectively, the said insulator end of'the rod having a threaded portion removably screwed directly into the insulator for the purpose specified.

site ends of the rod to the terminal block and lo 4'. A spark plug or the character shown in claim 25 3' exemplified by having the terminal block threaded into the insulator with the center rod held therein by a set screw.

CHARLES PATOCK. 

